Substack · Product sense · Entry · 45 to 60 minutes

What should readers see first in the app?

Substack is a platform where writers publish subscription based newsletters, posts, and other reader experiences, and readers follow or pay for the writers they value. Answer this product management case and get it graded line by line against a weighted rubric.

Product sense
Prioritization
User empathy
Metrics thinking
Tradeoff analysis

The situation

The mobile product lead at Substack asks you to recommend what readers should see when they open the app. The app already matters to writer growth, with more than 25 percent of subscriptions in the network originating there, but the entry experience is not clearly optimized for one main job. Some readers open the app to catch up on writers they already subscribe to, especially paid subscriptions and items they have saved. Others want help discovering new writers, posts, and social activity across the network. Both behaviors matter, but the team is worried about a real tradeoff. If discovery is too aggressive, loyal readers may miss the writing they already value. If the app focuses only on catch up, it may limit growth for newer writers and reduce the app's role in helping readers find new voices. You are preparing a proposal for the next mobile release. Recommend the primary structure of the first screen, who it should serve first, what content deserves the highest priority, and how Substack should measure whether the change works.

What to produce

Write a 1 page product brief, about 500 to 700 words.

Your answer must

State the primary user need the first screen should solve, and name the main reader segments you considered.
Recommend a clear first screen structure, including what belongs at the top and what, if anything, should appear lower on the screen.
Explain how your proposal balances retention for existing readers with discovery for new writers and posts.
Define one primary success metric and at least two supporting or guardrail metrics tied to reader behavior and writer outcomes.
Describe the main tradeoffs or risks in your approach, and propose one simple test or rollout plan to validate it.

Constraints

Focus on the mobile app only, not email or the web product.
Keep subscriptions central to the experience, do not assume a pivot to ad driven engagement.
Scope your proposal to one release centered on the first screen, not a full rebuild of recommendations, social features, or account systems.

Format

Use short sections with headings such as goal, users, proposal, metrics, and risks.

How Substack actually played it

Substack describes a Home tab with a reading queue of new posts at the top and an explore feed below. The queue prioritises paid subscriptions, saved items and regular reads to improve writer retention, while the feed introduces new voices. It is a clear example of designing one screen to serve existing readers and discovery together.

Put what the user already values first to protect retention.
Add discovery below the fold of the core use case, not in place of it.
Reference the metric the change should move (over 25 percent of subscriptions originated in the app).
Keep subscriptions as the foundation even as social features grow.

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